One day, Kenichi meets Yuri, a foreign girl who is being chased by someone. In front of Hattori-kun and the Perman team, a mysterious masked monster named Psychoman, who can also levitate, appears. Psychoman, who plans to use his supernatural powers to conquer the world, forms an esper army of his own kind...

Hattori-kun received a letter from Iga's father asking him to take his friends and return home for spring break. Hattori-kun leaves for Iga with his younger brothers Shinzo, Kenichi, Yumeko-chan, and others. However, a suspicious shadow stares at the group... He is a subordinate of the scientific ninja Mechamaro, who has replaced the power of ninjutsu with the power of science. Mechamaro was plotting to confront Hattori-kun in order to prove the strength of scientific ninjas. And in order to occupy Iga no Sato, Hattori-kun sends a fake letter...

Anime film based on the novel "813" by Maurice Leblanc.